OF_setprop
len = OF_setprop(node, buf, value, op->op_buflen + 1);
int OF_setprop(int handle, char *prop, void *buf, int len);
len = OF_setprop(node, name, value, op->op_buflen + 1);
int OF_setprop(u_int handle, char *prop, void *buf, int len);
int OF_setprop(int, char *, const void *, int);